Effect of H2S on hydrate formation curve.
Effect of H2S on hydrate formation curve.
(OP)
Friends,
I work in a gas processing plant. We recently have encountered a hydrate formation in one of our subsea pipelines. Though a lot of study was made on hydrate prevention, and the requisite KHI dosing was commenced as per guidelines l;aid down, we still had a hydrate problem, whcih could only be cleared after MEG injection.The gas is sour, and wet. We had clear guideliens at what temperatures to inject Kinetic hydrate inhibitor and at what temperatures to inject MEG. Intially KHI was injected, and with further lowering of temperatures MEG was injected. The KHI was continued and MEG was stopped. After stoppage of MEG within 10 hrs hydrate plugging happened.The lab results had validated effectiveness of the selected KHi for hydrate inhibition.Since the hydrate formation happened despite this, I am interested in knowing what could have gone wrong? My doubts are as under:
1.0 Was the hydrate temp prediction erratic? How much does the hydrate temp change in presence of H2S and without H2S?
2.0 Is there any empirical correlation available which uses the pipelien pressures to estimate hydrate forming temperatures?
3.0 If these temp were a result of simulation and lab studies on KHI, what would have been the error in not feeding the correct avg gas composition?
Top those of you who might need any further data I am most willing.
I work in a gas processing plant. We recently have encountered a hydrate formation in one of our subsea pipelines. Though a lot of study was made on hydrate prevention, and the requisite KHI dosing was commenced as per guidelines l;aid down, we still had a hydrate problem, whcih could only be cleared after MEG injection.The gas is sour, and wet. We had clear guideliens at what temperatures to inject Kinetic hydrate inhibitor and at what temperatures to inject MEG. Intially KHI was injected, and with further lowering of temperatures MEG was injected. The KHI was continued and MEG was stopped. After stoppage of MEG within 10 hrs hydrate plugging happened.The lab results had validated effectiveness of the selected KHi for hydrate inhibition.Since the hydrate formation happened despite this, I am interested in knowing what could have gone wrong? My doubts are as under:
1.0 Was the hydrate temp prediction erratic? How much does the hydrate temp change in presence of H2S and without H2S?
2.0 Is there any empirical correlation available which uses the pipelien pressures to estimate hydrate forming temperatures?
3.0 If these temp were a result of simulation and lab studies on KHI, what would have been the error in not feeding the correct avg gas composition?
Top those of you who might need any further data I am most willing.





RE: Effect of H2S on hydrate formation curve.
H2S is known as substance which increases hydrate formation temperature at given pressure. I suggest you to go through GPSA book and find very useful data for combating against your problem.
Furthermore, visit Gas Liquid Engineering website, http://www.gasliquids.com/ and you will also find a lot of good references there. Mr Carroll's book, amongst others, is highly recommended material.
Based on my experience with process simulation software, there is no 100% reliable source for predicting hydrate equilibrium conditions, especially if 2- or 3-phase fluids are involved. However, HYSYS is rated very high for these calculations and you might want to use it and compare its outputs with laboratory data.
Best of luck,
http://antwrp.gsfc.nasa.gov/apod/astropix.html
RE: Effect of H2S on hydrate formation curve.